CONTACT: TOM MOORE
Joint Office for Planning, Marketing and Communications
8788 John Pappajohn Pavilion
Iowa City IA 52242
Release: Nov. 14, 2001
EMBARGOED UNTIL 4 P.M. CST WEDNESDAY, NOV. 14
Warfarin, aspirin provide similar benefits in stroke prevention
IOWA CITY, Iowa -- Research results from a $35 million, eight-year study
involving more than 2,000 patients show that aspirin and warfarin are essentially
comparable in their ability to prevent recurrent strokes in patients who have
had a prior ischemic stroke and did not have atrial fibrillation. The results
are published in the Nov. 15 issue of the New England Journal of Medicine.
After a decade of earlier research that verified the drug's benefit, physicians
now routinely prescribe the blood thinner warfarin to prevent first and recurrent
strokes in individuals who have atrial fibrillation, a condition characterized
by an irregular and rapid rhythm in the atrial chambers of the heart. People
with atrial fibrillation are at risk for stroke because pooled blood in their
hearts can lead to clots which, dislodged and carried to the brain (a process
known as embolism), can occlude brain arteries, blocking blood flow, resulting
in brain damage known as an ischemic stroke. Because warfarin use has a reputation
for complications in the form of hemorrhage, many physicians have been hesitant
for its use even in atrial fibrillation.
Until now there has been no research about warfarin's value compared to
aspirin in the prevention of stroke in the majority of people who do not have
atrial fibrillation yet have had a prior ischemic stroke. A University of
Iowa Health Care team, including Harold Adams, M.D., and Patricia Davis, M.D.,
participated a in the multi-center trial, which was coordinated by physicians
at Columbia University.
"We already knew that treating patients with either aspirin or warfarin
helped prevent another stroke," Adams said. "Now, we also know that
it is safe to use aspirin or warfarin therapy, whether the patient has atrial
fibrillation or not."
The study included 2,206 individuals who had suffered from an ischemic stroke
due either to local blockage in the brain vessels from hardening of the arteries
or from a clot arising from a source outside the brain carried through arteries
to the brain vessels. The study did not include patients whose stroke was
associated with atrial fibrillation (approximately 15 percent of all cases
of stroke) or from any form of hemorrhage (approximately 20 percent of all
In the study, half the patients received warfarin and the other half took
aspirin, each patient receiving pills that appeared to be warfarin or aspirin,
in a fashion known as double-blind, in which neither the patients nor the
investigators were aware of who received which medication. Since individuals
who take warfarin need to have their blood monitored for its ability to clot,
the investigators were sent true laboratory values for those patients actually
on warfarin but for those on aspirin, they were sent false values, values
which suggested the patients were actually on warfarin therapy.
After analyzing the data, the researchers found that the group of patients
taking aspirin had no statistically significant differences in the risk in
having a subsequent stroke as the group taking warfarin. There was also no
statistically significant difference in the risk of major bleeding in either
of the two groups.
Aspirin, with its low cost, wide availability, ease of use and lack of need
for the monitoring needed for warfarin, may remain the most widely used of
the two drugs, Adams says. Its use in combination with other drugs having
similar action seems promising. However, he also stressed that earlier concerns
that warfarin was a more hazardous therapy proved unfounded at the doses used
in the study. Those physicians having other indications for warfarin therapy
should take comfort in its comparative safety and efficacy even when there
is no atrial fibrillation present, and have no reason to switch to aspirin
should a stroke occur.
"This study shows that it is ultimately up to the patient and physician
to decide which therapy is the best course of action," Adams said.
Although both drugs will provide a reduction in the risk of having another
stroke, the research showed that at least 8 percent per year of the patients
taking either warfarin or aspirin still experience another stroke. Adams says
further research is ongoing to develop new methods to reduce this continuing
Stroke is the third largest cause of death in the United States, ranking
behind "diseases of the heart" and all forms of cancer, according
to the American Heart Association. Stroke is a leading cause of serious, long-term
disability in the United States, the heart association says. Approximately
500,000 people suffer a new stroke each year; an additional 100,000 cases
are recurrent attacks.
The symptoms of a stroke include a sudden numbness or weakness of the face,
arms or legs, especially on one side of the body, a sudden loss of vision
in one or both eyes, a severe headache, sudden confusion, trouble speaking
or understanding, and sudden trouble walking, dizziness or loss of balance
and coordination. Such symptoms are signs of a potential "brain attack"
and require immediate medical evaluation. Neurologists say when treatment
for stroke begins soon after the onset of symptoms there is a much greater
likelihood for recovery.
The National Institute of Neurological Disorders and Stroke funded the trial.
Bayer Corp. provided aspirin and placebo aspirin at no cost for the study.
DuPont Pharmaceuticals Co. donated the warfarin and placebo-warfarin and provided
$600,000 for the formulation of both the medications used in the trial. The
findings of the study affect approximately 70 percent of all stroke patients;
only 15 percent of patients with ischemic stroke also have atrial fibrillation.
University of Iowa Health Care describes the partnership between
the UI College of Medicine and the UI Hospitals and Clinics and the patient
care, medical education and research programs and services they provide. Visit
UI Health Care online at www.uihealthcare.com.